Adaptive bandwidth distribution system for high-performance input/output devices with variable throughput

Abstract

A method for issuing shadow requests to manage bandwidth allocation between an application that issues input/output (I/O) operation requests and an I/O device. A bandwidth manager detects the completion of an I/O operation, which includes either a read operation or a write operation. The bandwidth manager calculates a statistical duration for future I/O operations between the application and the I/O device based on throughput statistics related to past I/O operations. The bandwidth manager generates a shadow request for reserving a position in a queue that stores pending I/O requests for the I/O device for a first future I/O operation request from the application and having a duration related to the statistical duration, and inserts the shadow request into the queue. Advantageously, applications that do not make frequent I/O operation requests in advance may still execute I/O operations because bandwidth is reserved for future I/O operation requests via the shadow requests.

1. A method for issuing shadow requests to manage bandwidth allocation between an application that issues input/output (I/O) operation requests and an I/O device, the method comprising:
 detecting the completion of an I/O operation that includes either a read operation from the I/O device to the application or a write operation from the application to the I/O device; 
 calculating a statistical duration for future I/O operations between the application and the I/O device based on throughput statistics related to past I/O operations between the application and the I/O device; 
 generating a first shadow request for reserving a first position in a queue that stores pending I/O requests for the I/O device for a first future I/O operation request from the application and having a duration related to the statistical duration; and 
 inserting the first shadow request into the queue. 
 
     
     
       2. The method of  claim 1 , further comprising the step of calculating an I/O operation request frequency reflecting the rate at which the application issues I/O operation requests to the I/O device and based on an average interval between timestamps recorded when the application issues I/O operation requests to an application programming interface. 
     
     
       3. The method of  claim 2 , further comprising the steps of generating a second shadow request for reserving a second position in the queue for a second future I/O operation request from the application, and inserting the second shadow request into the queue based on the I/O operation request frequency. 
     
     
       4. The method of  claim 3 , wherein the first shadow request and the second shadow request are separated from each other in the queue by the average interval. 
     
     
       5. The method of  claim 1 , wherein the step of calculating includes determining an average amount of data being transferred during I/O operations between the application and the I/O device based on information received from an application programming interface. 
     
     
       6. The method of  claim 1 , wherein the throughput statistics include the available bandwidth of the I/O device. 
     
     
       7. The method of  claim 1 , wherein the throughput statistics are used to compute average values for the statistical duration over a period of time. 
     
     
       8. The method of  claim 1 , wherein the I/O device comprises a hard disk, a memory, a computer monitor, or a disc drive. 
     
     
       9. The method of  claim 1 , wherein the duration is substantially equal to the statistical duration. 
     
     
       10. A computer-readable medium storing instructions that, when executed by a processor, cause a bandwidth manager to issue shadow requests to manage bandwidth allocation between an application that issues input/output (I/O) operation requests and an I/O device, by performing the steps of:
 detecting the completion of an I/O operation that includes either a read operation from the I/O device to the application or a write operation from the application to the I/O device; 
 calculating a statistical duration for future I/O operations between the application and the I/O device based on throughput statistics related to past I/O operations between the application and the I/O device; 
 generating a first shadow request for reserving a first position in a queue that stores pending I/O requests for the I/O device for a first future I/O operation request from the application and having a duration related to the statistical duration; and 
 inserting the first shadow request into the queue. 
 
     
     
       11. The computer-readable medium of  claim 10 , further comprising the step of calculating an I/O operation request frequency reflecting the rate at which the application issues I/O operation requests to the I/O device and based on an average interval between timestamps recorded when the application issues I/O operation requests to an application programming interface. 
     
     
       12. The computer-readable medium of  claim 11 , further comprising the steps of generating a second shadow request for reserving a second position in the queue for a second future I/O operation request from the application, and inserting the second shadow request into the queue based on the I/O operation request frequency. 
     
     
       13. The computer-readable medium of  claim 12 , wherein the first shadow request and the second shadow request are separated from each other in the queue by the average interval. 
     
     
       14. The computer-readable medium of  claim 10 , wherein the step of calculating includes determining an average amount of data being transferred during I/O operations between the application and the I/O device based on information received from an application programming interface. 
     
     
       15. The computer-readable medium of  claim 10 , wherein the throughput statistics include the available bandwidth of the I/O device. 
     
     
       16. The computer-readable medium of  claim 10 , wherein the throughput statistics are used to compute average values for the statistical duration over a period of time. 
     
     
       17. The computer-readable medium of  claim 10 , wherein the I/O device comprises a hard disk, a memory, a computer monitor, or a disc drive. 
     
     
       18. The computer-readable medium of  claim 10 , wherein the duration is substantially equal to the statistical duration. 
     
     
       19. A system for issuing shadow requests to manage bandwidth allocation between an application that issues input/output (I/O) operation requests and an I/O device, the system comprising:
 a memory; and 
 a processor configured to: 
 detect the completion of an I/O operation that includes either a read operation from the I/O device to the application or a write operation from the application to the I/O device; 
 calculate a statistical duration for future I/O operations between the application and the I/O device based on throughput statistics related to past I/O operations between the application and the I/O device; 
 generate a first shadow request for reserving a first position in a queue that stores pending I/O requests for the I/O device for a first future I/O operation request from the application and having a duration related to the statistical duration; and 
 insert the first shadow request into the queue.